Voice mail is a feature of modern telephone systems that allows a calling party to leave a message for subsequent retrieval by a called party. It is normally subsequently retrieved by the called party (i.e. the intended recipient) by issuance of a command or series of commands to the telephone system that has stored the message for such later retrieval. The voice mail feature is most often used when the called party does not answer the incoming call and the incoming message is automatically redirected to the subscriber's voice mailbox.
The voice mail process involves the storage of a recorded voice message on storage equipment associated with the telephone switching network. The called party retrieves the message at a subsequent time when he/she issues a command or series of commands through his/her subscriber set to the storage equipment of the telephone network. In conventional land switched telephone networks, the called party is notified by a message waiting lamp (e.g. visual indicator light) included with the subscriber telephone set. Different notification techniques are provided with differing subscriber equipment.
Cellular mobile radiotelephones are connected, via radio, to the land public telephone network and hence voice mail messages may be directed to storage equipment associated with a mobile radiotelephone system. However a message waiting lamp is not presently available on commercially available mobile radiotelephones. The mobile subscriber must be notified of this voice mail message so that action may be taken to retrieve it, by having the stored message read out through his/her mobile radiotelephone.